Abstract

The antigenic topography of the closely related molecules human follicle stimulating hormone (hFSH), human chorionic gonadotropin (hCG), and human luteinizing hormone (hLH) was previously elucidated (1–3) with extensively characterized monoclonal antibodies (MCA) against hFSH (1), hCG (4), bovine LH (bLH) (5), and the free subunits of hCG (6). The structural similarities of the glycoprotein hormones are well established (7); they all consist of 2 subunits designated α and β. In humans, the former is encoded by a single gene and is thus identical for each member of this family, whereas the latter is different from hormone to hormone and is therefore known to mediate biological specificity. Schematic epitope maps were taken as a basis for the alignment of antigenic and receptor interaction domains. The aim of the present study was to localize epitopes on hFSH at the amino acid sequence level with synthetic peptides and to describe the biological role they may play. We focused on the question of whether and, if so, in which way MCA and synthetic peptides interfere with hFSH receptor (hFSH-R) interaction.